imx6: Add imx6_src_get_boot_mode

For i.MX6, the bootmode determine code is part of spl_boot_device,
but there is might be a possibility for other part the code need to
check the desired boot mode for adding new functionalities like
modeboot env variable, or changing boot order etc.

So introduced imx6_src_get_boot_mode which actually reading the
boot mode register for desired modes.

More cleanup will be add in future patches.

Cc: Stefano Babic <sbabic@denx.de>
Cc: Tim Harvey <tharvey@gateworks.com>
Cc: Matteo Lisi <matteo.lisi@engicam.com>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@openedev.com>
Reviewed-by: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/include/asm/imx-common/sys_proto.h b/arch/arm/include/asm/imx-common/sys_proto.h
index 732b692..631ccc5 100644
--- a/arch/arm/include/asm/imx-common/sys_proto.h
+++ b/arch/arm/include/asm/imx-common/sys_proto.h
@@ -8,6 +8,7 @@
 #ifndef _SYS_PROTO_H_
 #define _SYS_PROTO_H_
 
+#include <asm/io.h>
 #include <asm/imx-common/regs-common.h>
 #include <common.h>
 #include "../arch-imx/cpu.h"
@@ -40,6 +41,19 @@
 
 #define is_mx7ulp() (is_cpu_type(MXC_CPU_MX7ULP))
 
+#ifdef CONFIG_MX6
+#define IMX6_SRC_GPR10_BMODE		BIT(28)
+
+static inline u8 imx6_is_bmode_from_gpr9(void)
+{
+	struct src *psrc = (struct src *)SRC_BASE_ADDR;
+
+	return readl(&psrc->gpr10) & IMX6_SRC_GPR10_BMODE;
+}
+
+u32 imx6_src_get_boot_mode(void);
+#endif /* CONFIG_MX6 */
+
 u32 get_nr_cpus(void);
 u32 get_cpu_rev(void);
 u32 get_cpu_speed_grade_hz(void);